diff --git a/pydantic/main.py b/pydantic/main.py
index 01afe5fc65..3228e833c0 100644
--- a/pydantic/main.py
+++ b/pydantic/main.py
@@ -420,10 +420,10 @@ def _init_private_attributes(self) -> None:
     def dict(
         self,
         *,
-        include: Union['AbstractSetIntStr', 'MappingIntStrAny'] = None,
-        exclude: Union['AbstractSetIntStr', 'MappingIntStrAny'] = None,
+        include: Optional[Union['AbstractSetIntStr', 'MappingIntStrAny']] = None,
+        exclude: Optional[Union['AbstractSetIntStr', 'MappingIntStrAny']] = None,
         by_alias: bool = False,
-        skip_defaults: bool = None,
+        skip_defaults: Optional[bool] = None,
         exclude_unset: bool = False,
         exclude_defaults: bool = False,
         exclude_none: bool = False,
@@ -456,10 +456,10 @@ def dict(
     def json(
         self,
         *,
-        include: Union['AbstractSetIntStr', 'MappingIntStrAny'] = None,
-        exclude: Union['AbstractSetIntStr', 'MappingIntStrAny'] = None,
+        include: Optional[Union['AbstractSetIntStr', 'MappingIntStrAny']] = None,
+        exclude: Optional[Union['AbstractSetIntStr', 'MappingIntStrAny']] = None,
         by_alias: bool = False,
-        skip_defaults: bool = None,
+        skip_defaults: Optional[bool] = None,
         exclude_unset: bool = False,
         exclude_defaults: bool = False,
         exclude_none: bool = False,
@@ -621,9 +621,9 @@ def _copy_and_set_values(self: 'Model', values: 'DictStrAny', fields_set: 'SetSt
     def copy(
         self: 'Model',
         *,
-        include: Union['AbstractSetIntStr', 'MappingIntStrAny'] = None,
-        exclude: Union['AbstractSetIntStr', 'MappingIntStrAny'] = None,
-        update: 'DictStrAny' = None,
+        include: Optional[Union['AbstractSetIntStr', 'MappingIntStrAny']] = None,
+        exclude: Optional[Union['AbstractSetIntStr', 'MappingIntStrAny']] = None,
+        update: Optional['DictStrAny'] = None,
         deep: bool = False,
     ) -> 'Model':
         """
@@ -805,8 +805,8 @@ def _iter(
         self,
         to_dict: bool = False,
         by_alias: bool = False,
-        include: Union['AbstractSetIntStr', 'MappingIntStrAny'] = None,
-        exclude: Union['AbstractSetIntStr', 'MappingIntStrAny'] = None,
+        include: Optional[Union['AbstractSetIntStr', 'MappingIntStrAny']] = None,
+        exclude: Optional[Union['AbstractSetIntStr', 'MappingIntStrAny']] = None,
         exclude_unset: bool = False,
         exclude_defaults: bool = False,
         exclude_none: bool = False,